WASHINGTON -- The Supreme Court struck down a federal law Thursday that made it a crime to falsely claim being awarded a top military honor, saying the law infringed on the Constitution's First Amendment protection of free speech.

The court ruling concerned the Stolen Valor Act, under which a Pomona man, Xavier Alvarez, was convicted for claiming falsely in 2007 that he had been awarded the Medal of Honor, the nation's highest award for valor.

But Alvarez's attorneys convinced a lower court that his untruths were protected by the First Amendment's guarantee of free speech. And Thursday the Supreme Court agreed.

"Content based restrictions on speech have been permitted only for a few historic categories ... including incitement, obscenity, defamation," the court wrote.

Veterans groups expressed dismay.

"The Veterans of Foreign Wars of the U.S. is greatly disappointed," the organization's commander in chief, Richard Denoyer, said in a statement. "Despite the ruling, the VFW will continue to challenge far-fetched stories, and to publicize these false heroes to the broadest extent possible as a deterrent to others."

The penalty increases to a year in prison if the person lies about a Purple Heart, a Medal of Honor or another particularly high honor.

There was no question that Alvarez lied. After winning a seat on Southern California's Three Valleys Municipal Water District board of directors in 2007, he introduced himself by saying: "I'm a retired Marine of 25 years. I retired in the year 2001. Back in 1987, I was awarded the Congressional Medal of Honor. I got wounded many times by the same guy."

None of that was true. But a district judge overturned Alvarez's conviction by declaring the law a violation of the First Amendment.